IO 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



Frequency at different depths 



Fathoms 



O-IOO 



I0O-200 



2OO-30O 



3OO-4OO 



4OO-5OO 



50O-60O 



600-700 



7OO-80O 



80O-9OO 



9OO-IOOO 



IO0O-I50O 



150O-2OOO 



2000-3000 



Frequency at different temperatures 



Degrees 

 Fahrenheit 



80-75 

 75-70 

 70-65 

 65-60 

 60-55 

 55-50 

 50-45 

 45-40 

 40-35 

 35-30 

 30-25 



Average depth 



Average temperature 



i. Five basals. 



761 fathoms 

 49.0 Fahr. 



713 fathoms 



54. 1 ° Fahr. 



Bathymetric 

 range 



Pentacrinitidse 5-1350 



Apiocrinidse 565-940 



Phrynocrinidae 508-703 



Bourgueticrinidas 62-2690 



Plicatocrinidae (C alamo crinus) . . . .392-782 



2. Less than five basals. 



Bathymetric 

 range 



Plicatocrinidae (except Calamo- 

 crinus) 266-2575 



Thermal 

 range 



36.O-71.O 



36.7-38.I 



38.I-4O.O 



29.I-70.75 



38.5-43.9 



Thermal 

 range 



3LI-43-9 



The number of the basals in the crinoids, like the number of the 

 corresponding plates, the genitals, in the urchins, appears funda- 

 mentally to be five. 



Variation from this number, which is always by reduction, appears 

 invariably to be an indication of specialization, for it always occurs 

 in correlation with specialization in other directions. 



The reduction in the number of basals from five to three is an 

 example of specialization through suppression; though the reduc- 

 tion is by coalescence and not by loss of two of the original five, and 

 therefore all of the original substance included in the primitive five 

 basals is equally included in the specialized three, the segregation of 

 four into two pairs indicates a suppression of the individuality of 

 the units involved, though without an actual loss of their substance. 



